Declining petroleum supplies around the world have led to the increasing necessity to secure domestic oil supplies and develop an economic and highly effective renewable replacement for fossil fuels. Increased public awareness on the imbalance of atmospheric CO2 emissions from the extensive use of non-renewable fossil fuels has put pressure on industrialized countries to demand the gradual integration of biomass-derived fuels into their transportation sectors. Lignocellulosic biomass is the most abundant resource of organic carbon on Earth and is the only renewable resource that is cheap enough to replace fossil fuels and sustain energy demands in the transportation sector. Such biomass is composed of three major polymeric components: cellulose, hemicellulose, and lignin. Cellulose is crystalline in structure and is comprised of linear β-1,4 linked glucose units known as glucan. Hemicellulose is amorphous in structure and is often primarily comprised of polymeric chains of β-1,4 linked xylose units known as xylan, a major hemicellulose component in most hardwood species, agricultural residues, and herbaceous energy crops. Lignin is a cross-linked heterogeneous complex covalently bonded to hemicellulose involving polymers of phenyl propanol units called monolignols. Only the maximum utilization of these three components from lignocellulosic biomass to produce reactive intermediates, including fuel precursors, will allow the economic production of biofuels to sustain current and future energy demands.